1. Field of the Invention
The present invention related to a traction control of automobiles, and more particularly, to a traction control device automatically adapted to selections of transmission gear ratios of the speed change gear device for a relatively high speed driving and a relatively low speed driving.
2. Description of the Prior Art
The four wheel drive automobiles are generally constructed to have a pair of front wheels, a pair of rear wheels, an engine, and a transmission system including a speed change gear device for selectively providing a plurality of transmission gear ratios, a center differential device, a front differential device, and a rear differential device, the transmission system transmitting rotational output power of the engine to the pair of front wheels and the pair of rear wheels with the engine output power being divided by the center differential device into a front drive power part for driving the pair of front wheels and a rear drive power part for driving the pair of rear wheels, the front drive power part being further divided by the front differential device between the pair of front wheels, while the rear drive power part being divided by the rear differential device between the pair of rear wheels.
In the New Model Introduction Manual of PAJERO of Mitsubishi Motor Corporation issued on January 1991, there is described a four wheel drive automobile having a transmission device incorporating an automatic locking up control of the center differential device interrelated with the speed stage shifting of the transmission device, so that the automobile is driven with the center differential device being automatically locked up when the transmission device is shifted for driving the automobile on a rough road, sand or a snow ground or for climbing a steep uphill, so as to suppress a substantial difference of slippage which would occur between the front and rear wheels in those operating conditions.
On the other hand, in the modern automobiles in which the behavior control systems are incorporated so as to automatically control the running behavior, particularly turning behavior of the automobiles against spinning or drifting out, the automobiles are each equipped with a brake system for selectively braking each of the pairs of front and rear wheels independently of the others under the control of a micro-computer which conducts certain behavior control calculations.